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Re: [Xen-users] Re: [Xen-devel] VM disk I/O limit patch

To: Florian Heigl <florian.heigl@xxxxxxxxx>
Subject: Re: [Xen-users] Re: [Xen-devel] VM disk I/O limit patch
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Wed, 22 Jun 2011 09:07:10 -0400
Cc: Andrew Xu <xu.an@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, xen-users@xxxxxxxxxxxxxxxxxxx
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On Wed, Jun 22, 2011 at 02:16:09PM +0200, Florian Heigl wrote:
> Hi,
> relying on DM is not advisable since this is yet another layer that
> breaks write barriers, plus it kills portability to non-linux OS.

How so? And write barriers don't exist anymore - I think you mean
flush support. And I believe they are fixed now - flush requests
are passed through to the bottom layer (the real disk). But let
me double check that shortly.

Portability to non-linux OS? ? What do you mean by that? As in using
this patch on NetBSD or OpenSolaris backend? The backend in those
OS-es is quite different so it wouldn't be "portable"

> btw:
> It would be cool if a block shaping patch finally made it in the Xen
> mainline, since the last one that was submitted in 2009 was apparently
> forgotten...

Why can't dm-ioband do this for you? Hm, I don't remember seeing that patch
at all?

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